1. Field of the Invention
The present invention relates to a radiation image converting panel comprising a radiation converting film having a columnar crystal structure, which converts an incident radiation ray to a visible light.
2. Related Background Art
Radiation images typified by X-ray images have conventionally been widely used for a purposes such as disease diagnosis. As a technique for obtaining such a radiation image, for example, a radiation image recording and reproducing technique using a radiation converting film that accumulates and records irradiated radiation energy, and also emits a visible light according to radiation energy accumulated and recorded as a result of irradiating an excitation light has been widely put into practical use.
A radiation image converting panel to be applied to such a radiation image recording and reproducing technique as this includes a support body and a radiation converting film provided on the support body. As the radiation converting film, a photostimulable phosphor layer having a columnar crystal structure formed by vapor-phase growth (deposition) has been known. When the photostimulable phosphor layer has a columnar crystal structure, since a photostimulable excitation light or photostimulable emission is effectively suppressed from diffusing in the horizontal direction (reaches the support body surface while repeating reflection at crack (columnar crystal) interfaces), this allows remarkably increasing the sharpness of an image by photostimulable emission.
For example, Japanese Patent Application Laid-Open No. 2003-028994 (Document 1) describes a technique that reduces a luminance unevenness by uniforming a concentration distribution of activator along a film thickness direction of phosphor layer. On the other hand, Japanese Patent Application Laid-Open No. 2005-091146 (Document 2) describes a technique that reduces a luminance unevenness by uniforming a concentration distribution of activator in a phosphor layer.